Monthly Archives: November 2011

Well, time for my second dive with my new Poseidon Discovery MkVI. Did another 60 minutes benath the water, and it felt far more relaxed than the first dive. managed to stay within 0.5 meters in variation during the whole dive. A lot of different exercises, like sharing gas, buddy breathing, bail out to off board tank and so on. Did my first “swim without mask” since my first certification. It was somewhat different from open circuit.

First pool dive and spent almost two hours in the pool. About 60 minutes below surface. It was more crawling on the tiles than swimming around. But after some time i actually found some sort of buoyancy. Very strange feeling, not to make any bubbles. It feels like you are not breathing, you are not fed with pressurized air. You simply inhale by dragging the air into your lungs like you would do on land, although a bit harder, since you are pressurized.

As I said in my last post, I went for the Poseidon Discovery MkVI, and went with the PADI training course. At the moment they have two courses directed at rebreathers. I will combine these two into one big course. First course is the PADI “Rebreather Diver” which qualifies you for 18M. You need to be an OW diver and have 25 logged dives. The PADI “Advanced Rebreather Diver” qualifies you for 30M unless you are a Deep Diver, then you are certified for 40M. For the Advanced Rebreather course, you need to be certified AOW Diver and a certified Rebreather Diver. The big difference between the two courses are of course the ability to use a off board bail out tank and to show control of your skills at depth. The courses contains at least 200/240 min of UW time, and at least the same amount of theory.

So at the end of the two certifications I will have some 8 hours of dive time and trust me, I will need them. Diving with a close circuit rebreather is not easy, if you are used to open circuit. You simply cannot control your buoyancy with your respiration. But once you have achieved it, you stay there, no matter how you breathe. That is the upside. Another upside is of course that you could spend three hours at 20M if you’d like. Doing that on open circuit would require 16000 liters of gas, or quad 18L 200BAR and then some… ;)

Well, I have thought about it for some time. But when we where at Gullmarsfjorden in Sweden, there was this rebreather-diver in the group and even though he dived technical, it all seemed cool and on the last dive of the weekend I paired up with him on a dive down to 40M. Since I was on Open Circuit, and on Air, and on a no stop limit, I was the one forcing us up from 40M after a mere 8 minutes. Then we had a ascend to about 20M before my Mares icon HD told me that I had enough time to deco, to make a stop for a few minutes. Again being forced to a shallower depth by the no stop limit after approx 5 minutes. At 15M we had a nice swim back to entry point for about 16 minutes, followed by a 3 min safety stop at 5M before surfacing after 43 minutes. During the dive I used up 2900 liters of air. That is 208 BAR out of my starting pressure of 276. So, yes, I might had been able to squeeze out a couple of more minutes.

But when I calculated the dive with iDeco (dive planner) for a rebreather dive (CCR) I was a bit surprised. 15 Min @ 40M, 20 Min @ 30M followed by 60 Min @ 20M without Deco. So twice the bottom time, more time on 30M than I had on 15M on OC, followed by a whole 60 minutes on 20M. 95 minutes dive time, and only using roughly 96 liters of gas. This got me really interested in rebreathers. The ability to have much longer no stop limits. Of course, one could argue that you would have the same if you dived on Nitrox. Yes, if you had like five different mixes and a lot of tanks. I calculated the above dive on OC, result? 9600 liters of gas….

So I looked into the different rebreathers on the market, and since I am a recreational diver, I quickly dismissed the more technical ones. After looking at both the rEVO, the Inspiration Vision and Poseidon Discovery, I felt that the most advantages for me belonged to the Poseidon Discovery. It is a very light machine, and very simply to set-up and the Pre-Dive tests are mainly controlled by the on-board computer. There is of course a downside to things being controlled by a computer, but I have faith in that it will not send me diving unless it is completely sure. Make no mistake, diving a rebreather will require more of you, otherwise you might end up in the statistics. So I am starting my PADI Rebreather Diver and PADI Advanced Rebreather Diver in a couple of weeks.